The conglomerate is a medium to dark gray quartz pebble metaconglomerate with minor quartzite beds, interpreted as braided alluvial deposits.

[3] Detrital zircon geochronology yields a minimum age for the source regions of 1665 Mya, consistent with the formation being deposited in an extensional basin (the Pilar basin) opened during the transition from the Yavapai orogeny to the Mazatzal orogeny.

[4] The formation has been interpreted as a beach gravel[6] or as a high-energy fluvial deposit associated with the Pilar basin of the Yavapai orogeny.

[4] The unit was originally designated as the Big Rock conglomerate member of the Kiawa Mountain Formation by Fred Barker in 1958, during the mapping of the Las Tablas quadrangle.

[1] It was designated as a formation within the Vadito Group by Bauer and Williams in their sweeping revision of northern New Mexico Precambrian stratigraphy in 1989.